SEER Patterns of Care Studies describe, characterize, and compare practice patterns and treatments provided for cancer in different geographic areas of the United States. SEER Patterns of Care Studies are conducted to satisfy a Congressional directive (under Public Law 100-607, Sec. 413 (a)(2)(C) adopted November 4, 1988) to the National Cancer Institute to [unreadable]assess the incorporation of state-of-the-art cancer treatments into clinical practice and the extent to which cancer patients receive such treatments and include the results of such assessment in the biennial reports[unreadable][unreadable]. To select the cancers to satisfy this directive, the Division of Cancer Control and Population Sciences has been working closely with the Division of Cancer Treatment. This year[unreadable]s Pattern[unreadable]s of Care (POC) Study will investigate state-of-the-art therapies for prostate cancer, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and gastrointestinal stromal tumors.